1. Field of the Invention
The present invention relates to image processing technology, and in particular relates to local contrast enhancement technology.
2. Description of the Related Art
Various image enhancement approaches are used to improve image quality. One of the image enhancement approaches is contrast enhancement. Contrast enhancement is a procedure used to improve contrast in images. Compared with global contrast enhancement, local contrast enhancement can bring out more detail in an image. For local contrast enhancement, an image is first divided into several blocks, and then a procedure called histogram equalization is performed to each of the blocks so that the brightness values of pixels in a block are transformed based on a transformation function (contrast enhancement function) of the block. The image after histogram equalization looks inconsistent due to different average brightness from block to block.